Primary endpoint and analysis plan
The primary outcome was virologically confirmed, symptomatic COVID-19, defined as a NAAT-positive swab combined with at least one qualifying symptom (fever \(\ge\) 37.8°C, cough, shortness of breath, or anosmia or ageusia (103)
… each study had to meet prespecified criteria of having at least five cases eligible for inclusion in the primary outcome before a study was included in efficacy analyses (103)
Vaccine efficacy was calculated as 1 – adjusted relative risk (ChAdOx1 nCoV-19 vs control groups) computed using a Poisson regression model with robust variance (103)